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Written assignments

Use our simple guide to help you make the right choices with your punctuation

Using commas

Many people are unsure of how to use commas. This simple guide and examples should help you to make the right decision.

Misused commas can confuse the reader, cause a sentence to be meaningless or change the meaning of the sentence to something you didn't intend to say. Pay attention to placing the commas correctly to ensure accuracy and prevent confusion for the reader.

Using commas to divide items in a list

The usual rule is that there is no comma before the final item in the list, so another word is used instead of the comma. In most instances, that word will be 'and' or 'or'.

Example: Their essays focused on healthcare, therapy, nursing and rehabilitation.

Beware of extra 'and's

Sometimes an item within a list might include an 'and'. This will mean using an extra comma, known as the Oxford comma, in order to give the exact meaning for the reader.

Example: The sandwiches we wish to order today are cheese salad, egg and tomato, and ham.

The second comma is needed to separate out 'egg and tomato' as fillings for one sandwich. Otherwise, it would be unclear whether the customer wants one with egg and the other with tomato and ham, one with egg and tomato and the other with ham, or one with egg, one with tomato and one with ham.

Using commas after introductory phrases in sentences

An introductory word or phrase can be used to signal the continuation of a point, a change in direction or to emphasise an author. Most of these phrases need a comma after them to show where the main part of the sentence begins. The word or phrase before the comma can be helpful for the logic and flow of the text, but it could be removed without losing the meaning or the point which is being made.

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It's and its 

'Its' and 'it’s' are often confused. Here we explain the differences between them, and show when and where you should and shouldn't use them.

Note that you shouldn't use contractions in assignments.


This is the possessive pronoun, like 'my', 'your', and 'their'.


  • Every country has its traditions.
  • The horse shut its eyes and neighed.
  • This approach also has its disadvantages.

In contrast, possessive nouns do have an apostrophe, which stands for 'of' or 'belonging to'. It does not have to be a physical object.


  • Michael’s car broke down yesterday. (The car belonging to Michael).
  • It was Janet’s turn to lead the meeting. (The turn of Janet to lead).


The apostrophe indicates that this is a contraction that stands for 'it is' or 'it has'.

The apostrophe replaces the missing letters.


  • It’s snowing again. This is a contraction of 'it is'.
  • Have you seen my jacket? It’s disappeared. This is a contraction of 'it has'.
  • It’s probably true that most pop stars use Autotune. This is a contraction of 'it is'.

Download our 'it's and its' revision sheet

Download these tips as a PDF for your grammar and punctuation revision notes.

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